main Makefile: VegBIEN DB: Added functions schema targets

Makefile: $(confirm): Support a separate line outside of the highlighted line. Include the "Continue?" in the macro since all prompts include it.

Makefile: VegBIEN DB: Display different warning message depending on whether entire DB or just current public schema is being deleted

db_xml.py: put_table(): Recurse into forward pointers

sql.py: put_table(): Take multiple in_tables. Initial implementation just used the first in_table.

sql.py: Added add_row_num(). put_table(): Add row_num to pkeys_table, so it can be joined with in_table's pkeys.

sql.py: Added run_query_into() and use it in insert_select()

sql.py: pkey(): Support escaped table names

sql.py: mk_insert_select(): embeddable: Name the function alias "f" since it will just be wrapped in a nested SELECT, so the exact name doesn't matter (and won't be visible outside the nested SELECT anyway)

db_xml.py: put_table(): Return the (table, col) where the pkeys are made available, now that this information is available from sql.put_table()